| 1. |
- Ardeshiri, Tohid, et al.
(författare)
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Bicycle Tracking Using Ellipse Extraction
- 2011
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Ingår i: Proceedings of the 14thInternational Conference on Information Fusion, 2011. - : IEEE. - 9781457702679 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- A new approach to track bicycles from imagery sensor data is proposed. It is based on detecting ellipsoids in the images, and treat these pair-wise using a dynamic bicycle model. One important application area is in automotive collision avoidance systems, where no dedicated systems for bicyclists yet exist and where very few theoretical studies have been published. Possible conflicts can be predicted from the position and velocity state in the model, but also from the steering wheel articulation and roll angle that indicate yaw changes before the velocity vector changes. An algorithm is proposed which consists of an ellipsoid detection and estimation algorithm and a particle filter. A simulation study of three critical single target scenarios is presented, and the algorithm is shown to produce excellent state estimates. An experiment using a stationary camera and the particle filter for state estimation is performed and has shown encouraging results.
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| 2. |
- Axholt, Magnus, et al.
(författare)
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Optical See-Through Head Mounted Display : Direct Linear Transformation Calibration Robustness in the Presence of User Alignment Noise
- 2010
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Ingår i: Proceedings of the 54th Annual Meeting of the Human Factors and Ergonomics Society. - Linköping : Linköping University Electronic Press. - 9780945289371
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Konferensbidrag (refereegranskat)abstract
- The correct spatial registration between virtual and real objects in optical see-through augmented reality implies accurate estimates of the user’s eyepoint relative to the location and orientation of the display surface. A common approach is to estimate the display parameters through a calibration procedure involving a subjective alignment exercise. Human postural sway and targeting precision contribute to imprecise alignments, which in turn adversely affect the display parameter estimation resulting in registration errors between virtual and real objects. The technique commonly used has its origin incomputer vision, and calibrates stationary cameras using hundreds of correspondence points collected instantaneously in one video frame where precision is limited only by pixel quantization and image blur. Subsequently the input noise level is several order of magnitudes greater when a human operator manually collects correspondence points one by one. This paper investigates the effect of human alignment noise on view parameter estimation in an optical see-through head mounted display to determine how well astandard camera calibration method performs at greater noise levels than documented in computer vision literature. Through Monte-Carlo simulations we show that it is particularly difficult to estimate the user’s eyepoint in depth, but that a greater distribution of correspondence points in depth help mitigate the effects of human alignment noise.
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| 3. |
- Blom, Jonas, et al.
(författare)
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Pole Placement Design of Power Control Algorithms
- 1999
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Ingår i: Proceedings of the 49th IEEE Vehicular Technology Conference. - Linköping : Linköping University Electronic Press. - 0780355652
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Konferensbidrag (refereegranskat)abstract
- Time delays reduces the performance of any controlled system. If neglected in the design phase, the system may even become unstable when using the designed controller. Several power control strategies have been proposed in order to improve the capacity of cellular radio systems, but time delays are usually neglected. Here, it is shown that the problems can be handled by considering the time delays in the design phase in order to choose the appropriate parameter values. Most popular algorithms can be seen as special cases of an integrating controller. This structure is extended first to a proportional integrating (PI)-controller and then further on to a general linear controller of higher orders. Corresponding design procedures are outlined based on techniques, such as pole placement, from the field of automatic control. The PI-controller is a very appealing choice of structure, with better performance compared to an I-controller and less complex than a higher order controller. The benefits are further illuminated by network simulations.
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| 4. |
- Boers, Yvo, et al.
(författare)
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A Track Before Detect Algorithm for Tracking Extended Targets
- 2006
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Ingår i: IEE Proceedings - Radar Sonar and Navigation. - : Institution of Engineering and Technology (IET). - 1350-2395 .- 1359-7086. ; 153:4, s. 345-351
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Tidskriftsartikel (refereegranskat)abstract
- For certain types of sensor-target configurations, a point target model or approach is not suitable and the physical extent of the target is accounted for during processing. An extended target track-before-detect (TBD) algorithm is presented and the performance is compared to an algorithm based on the point target assumption. Simulations illustrate the gain in performance obtained by using the extended target model where a particle filter is used for the TBD implementation.
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| 5. |
- Bshara, Mussa, et al.
(författare)
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Fingerprinting Localization in Wireless Networks Based on Received-Signal-Strength Measurements : A Case Study on WiMAX Networks
- 2010
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 59:1, s. 283-294
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers the problem of fingerprinting localization in wireless networks based on received-signal-strength (RSS) observations. First, the performance of static localization using power maps (PMs) is improved with a new approach called the base-station-strict (BS-strict) methodology, which emphasizes the effect of BS identities in the classical fingerprinting. Second, dynamic motion models with and without road network information are used to further improve the accuracy via particle filters. The likelihood-calculation mechanism proposed for the particle filters is interpreted as a soft version (called BS-soft) of the BS-strict approach applied in the static case. The results of the proposed approaches are illustrated and compared with an example whose data were collected from a WiMAX network in a challenging urban area in the capitol city of Brussels, Belgium.
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| 6. |
- Bshara, Mussa, et al.
(författare)
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Tracking in WiMAX Networks Depending on SCORE Measurements
- 2009
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Ingår i: Proceedings of the 6th Workshop on Positioning, Navigation and Communication. - 9781424432936 - 9781424432929 ; , s. 229-234
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Konferensbidrag (refereegranskat)abstract
- Tracking in WiMax networks is gaining a lot of interest; especially after the mobile WiMax became one of the emerging technologies that promote low-cost deployment and evolving to provide IP-based services of high mobility including providing location-based services (LBS). Therefore, locating users in a cheap way thatdepend on the available network resources is becoming more and more interesting and an active topic for researchers. In this paper we consider the problem of tracking in WiMAX networks depending on SCOREobservations. The provided examples show that with efficient measurement data processing and with the help of already available data (street maps), plausible results can be achieved.
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| 7. |
- Burak Guldogan, Mehmet, et al.
(författare)
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Gaussian mixture PHD filter for multi-target tracking using passive doppler-only measurements
- 2012
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Ingår i: IET Conference Publications. - : IEEE conference proceedings. - 9781849196246 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- In this paper, we analyze the performance of the Gaussian mixture probability hypothesis density (GM-PHD) filter in tracking multiple non-cooperative targets using a passive sensor network. Non-cooperative transmissions from illuminators of opportunity like GSM base stations, FM radio transmitters or digital broadcasters are exploited by non-directional separately located Doppler measuring sensors. Clutter, missed detections and multi-static Doppler variances are incorporated into a realistic multi-target scenario. Simulation results show that the GM-PHD filter successfully tracks multiple targets using only Doppler shift measurements in a passive multi-static scenario.
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| 8. |
- Carlemalm, Catharina, et al.
(författare)
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Detection and Discrimination of Double Talk and Echo Path Changes in a Telephone Channel
- 1998
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Ingår i: Signal Analysis and Prediction. - : Springer. - 0817640428 - 9780817640422 ; , s. 407-418
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- It is important to detect a change in the echo path quickly but not confuse it with double talk, since the echo canceler should react differently for these two phenomena. In this chapter, a sequential detection scheme is presented and, based on model assumptions, the maximum a posteriori probabilities of the occurrence of double talk and abrupt changes in the echo path are derived. By utilizing the fact that the most active part of a typical impulse response of a telephone channel is short and by using a low complexity time-delay estimation algorithm to find these most active taps and not estimating the rest of the taps, low computational complexity of the proposed detection method is achieved. The scheme is veried experimentally in computer simulations using a real speech signal and impulse responses created from measured impulse responses from real hybrids of a telephone channel.
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| 9. |
- Chandaria, Jigna, et al.
(författare)
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Real-Time Camera Tracking in the MATRIS Project
- 2006
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Ingår i: Prcoeedings of the 2006 International Broadcasting Convention.
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Konferensbidrag (refereegranskat)abstract
- In order to insert a virtual object into a TV image, the graphics system needs to know precisely how the camera is moving, so that the virtual object can be rendered in the correct place in every frame. Nowadays this can be achieved relatively easily in postproduction, or in a studio equipped with a special tracking system. However, for live shooting on location, or in a studio that is not specially equipped, installing such a system can be difficult or uneconomic. To overcome these limitations, the MATRIS project is developing a real-time system for measuring the movement of a camera. The system uses image analysis to track naturally occurring features in the scene, and data from an inertial sensor. No additional sensors, special markers, or camera mounts are required. This paper gives an overview of the system and presents some results.
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| 10. |
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